The president was "unscathed" after former FBI Director James Comey's testimony, but USA media leaks led to him being investigated as part of special counsel Robert Mueller's probe. Last week, during Comey's testimony, he said he believed he was terminated because of his investigation into Russia's influence on the election. "Nice", Trump wrote on Twitter, later repeating his accusation that the probe is a "witch hunt".

Mueller was appointed as special counsel to investigate Russian involvement in the 2016 presidential election and possible collusion by Trump campaign associates with the Russians, but there has been no indication that Mueller told Trump to fire Comey. He has already been subpoenaed by the House intelligence committee. Last week, former FBI Director James Comey told Congress he believed he was sacked by Trump to undermine the agency's Russian Federation investigation.

The order from the general counsel for the transition team casts a wide net on documents that could shed light on ties between Trump's presidential campaign and representatives of Russia's government.

Comey told Congress last week that he leaked his memos of his conversations Trump to a friend after a tweet by the president suggested he may have taped the conversations.

Dianne Feinstein, top Democrat on the Senate Judiciary Committee, said she was "increasingly concerned" that Trump will fire both Mueller and Rosenstein. The Post spoke with five people briefed on the inquiries, who spoke on the condition of anonymity because they were not authorized to discuss the probe publicly.

Although the investigation has not yet been confirmed, President Trump sent a tweet on Thursday which more or less affirmed he is being investigated.

The Twitter attacks came as Vice President Mike Pence hired a personal lawyer to represent him in the intensifying investigation.

Several congressional panels are also investigating the Russian Federation issue, which has cast a shadow over the early months of Trump's presidency. The newspaper noted Mueller had requested interviews with CIA Director Dan Coats, National Security Agency chief Michael Rogers and Richard Ledgett, the former NSA deputy director.

He wrote in multiple social media posts that he views Mueller - a long-serving former Federal Bureau of Investigation director respected by both parties - as leading a biased probe with the singular aim of dislodging Trump.

The president tweeted Friday, "The Fake News Media hates when I use what has turned out to be my very powerful Social Media - over 100 million people!"

He followed that up 12 minutes later with a second tweet: "Crooked H destroyed phones w/ hammer, "bleached" emails, & had husband meet w/AG days before she was cleared- & they talk about obstruction?"

Trump advisers and confidants describe the president as increasingly angry over the investigation, yelling at television sets in the White House carrying coverage and insisting he is the target of a conspiracy to discredit - and potentially end - his presidency. Mueller is now leading the investigation into whether Russian Federation interfered in the 2016 presidential election.